Erin Stead won that healthiest of picture-book prizes, the Caldecott Medal, for her illustrations for A Sick Day for Amos McGee. And she might have earned it for her fine draftsmanship alone.

Just as great painters may succeed at landscapes but fail at portraiture, some acclaimed picture-book illustrators can’t draw – and especially can’t draw faces – well. They excel at working with paint, collage, or mixed media instead of a pencil or pen. Or they illustrate stories good enough to mask or offset their deficiencies as draftsmen.

But pencil drawings have provided the spark for many of the best picture books of the past 50 years, including Caldecott winners such as Chris Van Allsburg’s Jumanji and Peter Spiers’s Noah’s Ark. And the medium may attract fewer illustrators as computer-generated art proliferates. So it’s cheering that Erin Stead shows a gift for the form in A Sick Day for Amos McGee, a picture book written by her husband, Philip. She draws with a pencil on softly colored woodblock prints to give warmth and depth to this comic fantasy about animals who repay the kindness of their zookeeper.

A Sick Day for Amos McGee has little in the way of plot. A faithful zookeeper always makes time to visit his animal friends – to play chess with an elephant and sit with a shy penguin – until the day he stays home in bed with a cold and he and his companions reverse their caretaking roles. The creatures help the sniffling Amos by assuming, as children tend to do, that others have needs identical to theirs. The rhino with allergies hands him a handkerchief. The owl who is afraid of the dark – “knowing that Amos was afraid of the dark” – reads him a story.

Philip Stead develops his theme — you get what you give — with an appealing absence of didacticism and pretense. But his writing has less power than that of Caldecott winners such as Where the Wild Things (in which the last line – “and it was still hot” – uplifts all that has preceded it). And A Sick Day for Amos McGee ends on a slightly derivative note when, in an echo of Goodnight Moon, everyone says “goodnight”:

So Amos said goodnight to the elephant. And good night to the tortoise. And goodnight to the penguin. And good night to the owl …

But Erin Stead extends the story with her talent for portraiture and more. Every face in the book — human or animal — shows emotion and personality, whether it’s that of the contemplative elephant, the long-suffering rhinoceros, or the sweetly child-like Amos. And Stead’s use of color heightens the mood she creates for each page. On several spreads, she sets her characters against wide, vertical yellow stripes that could represent wallpaper, beams of sunlight, and more. That several interpretations would make sense helps to show why this book would stand up to many rereadings.

No less appealing are the visual subplots. One involves the reticent penguin who at first holds himself apart from other characters. Then he catches a red balloon that floats within his reach at the zoo. We next see him holding the balloon as he sits at the front of a bus that is taking the animals to the ailing Amos: He’s starting to shed his shyness. On the following spread, he stands tall as he walks at the front of a line of larger animals marching into the sick zookeeper’s bedroom. He has clearly gained confidence from holding a balloon, what psychologists might call a “security object,” and perhaps also from his mission. Only the pictures tell you about the change in the penguin, but they need no help from words.

Was this book worthy of a Caldecott Medal? A qualified yes. Erin Stead gets an A for her art and Philip Stead a B/B+ for his writing. But American Library Association rules say that Caldecott judges should’t consider the text unless it interferes with the pictures. And the writing in this book doesn’t interfere. By the rulebook, A Sick Day for Amos McGee gets an A. The greatest Caldecott Medal winners – which include Virginia Lee Burton’s The Little House and Sendak’s Where the Wild Things Are – are A+ books in which the words and pictures are equally superlative. But only the most unrealistic adult would expect a child to read nothing but A+ books. And A Sick Day for Amos McGee has literary traits that some of the ALA titans don’t, including that it’s short and gentle enough to make a fine bedtime story for any child who is getting tired of Goodnight Moon.

Sendak once wrote that Randolph Caldecott’s work marks the beginning of the modern picture book. The Victorian illustrator found a new way to juxtapose words and pictures, he noted: “Words are left out – but the picture says it. Pictures are left out — but the word says it.” Long after Caldecott’s death, artists must still to bring those ideals into harmony, and Erin Stead has done it in A Sick Day for Amos McGee.

Best line/picture: Two wordless spreads that tell the story entirely in pictures.

Worst line/picture: I don’t have children, but people who do say that you need to be careful about introducing the concept of “fear of the dark” to toddlers and preschoolers who don’t have it. Some adults might want to skip over the lines that refer to it. And all of the characters in this book are male.

They are considered all male because of the use of the male pronouns he, his, himself. “the elephant arranged his pawn, tortoise stretched his legs, penguin sat patiently by himself, owl scratching his head, and the rhino and his allergies.”